(a) Field of the Invention
According to the present invention, hereinafter the term “LED” is the abbreviation of the light-emitting diode;
The present invention relates to a LED device with voltage-limiting unit and voltage-equalizing and current-limiting resistances, in which a LED is connected in parallel with a voltage-limiting unit, and a current-limiting resistance is connected in series between the connection joints of the LED and the voltage-limiting unit for limiting the shunt current passing through the voltage-limiting unit, and two ends of each LED are connected in parallel with an voltage-equalizing resistance, so when plural light-emitting units are connected in series (or series-parallel) for forming a light-emitting unit set, the end voltage of each LED can be stabilized.
(b) Description of the Prior Art
Conventional LEDs usually parallel connect with the voltage-limiting units in the same polarity at two ends of each LED, such as the zener diode, to constitute the light-emitting unit, thereby when the end voltage of LED is abnormally increased, the abnormal voltage is absorbed by the zener diode; however, when the light-emitting units being parallel connected by the above mentioned LED and the zener diode are series connected (including series-parallel connected) in plural sets to constitute the light-emitting unit, the voltage is not able to be evenly distributed due to the different properties of the LED and the zener diode, so that when subject to abnormal high voltage, the LED loaded with higher end voltage is passed by the higher current therefore the LED is often damaged.